St. Thomas Aquinas revives the teaching of Aristotle on chance and equivocal causality,

Does St. Thomas hold the principle of finality, that every agent acts according to an end? Yes, he does.41 The
principle is "Every agent acts for a goal" (Omne agens agit propter finem). Aquinas describes the principle in several
places: Aquinas Summa Contra Gentiles 3. 1; Aquinas Summa Contra Gentiles 3. 2; Aquinas Summa Theologiae,
2-2. 1. 2. Further, St. Thomas teaches that every creature (whether endowed with intelligence or not) acts for a goal: "Every
agent has some intention and desire of the end" (Aquinas Scriptum in Liber Sententiarum 1. 35. 1.1).42 Further,
the merit of Thomistic ontology, with respect to that of Aristotle, is the profound structure of being has found a place for
the explanation of desire.

How does St. Thomas define the final cause? St. Thomas notes that our internal experience tells us "that everything that
is produced through the will of an agent is directed to an end by the agent: because the good and the end are the proper object
of the will; wherefore, whatever proceeds from a will must needs be directed to an end. The good which is derived is the end,
and in regard to any particular action to be placed to attain it, it is called final cause" (Aquinas Summa Contra Gentiles
3. 1). In regard to non-rational creatures: "Other things that lack intellect do not direct themselves to their goal, but
are directed by another" (Aquinas Summa Contra Gentiles, 3. 1).43

Does St. Thomas affirm finality for non-rational creatures. St. Thomas teaches that nature acts for a definite end; since
a non-rational being is without intellect, this inclination to a determined end must have been impressed upon it by an intelligent
cause. St. Thomas says, "Every work of nature is the work of intelligence" (Aquinas De Veritate 5. 2. ad 5).44
St. Thomas also notes that "The determination of the agent to act, as in rational nature, happens by rational appetite, which
is called the will; in other things it happens by natural inclination, which is called the natural appetite" (Aquinas Summa
Theologiae 1-2. 1. 2).45

Is finality a natural orientation of things for St. Thomas? Yes, St. Thomas views nature as operating for some final cause.
St. Thomas says, "There is nothing in nature that is frustrated; because everything in nature exists for something else...So
therefore, since nature operates to benefit some thing, so natural things that were not able to attain to an end which nature
intended would be frustrated" (Aquinas In De Anima 3. 1. 17).46

Does St. Thomas agree with the Evolutionists that survival of the species is the ultimate activity of being? No, St. Thomas
holds that the full development of its own "to be" is the ultimate activity of being. St. Thomas says, "The ultimate act is
‘to be.’ Since ‘becoming’ is a passage from potency to act it is necessary that existence be the ultimate
act to which anything tends as it becomes something; and so the natural becoming tends toward what naturally is desired which
is this, existence, the ultimate act to which everything tends" (Aquinas Compendium Theologiae 1. 11. 21).47

Does St. Thomas affirm finality from the order and harmony of things joined together toward the "ultimate goal," despite
change? Yes, he does. St. Thomas teaches, "The same divine wisdom is the efficient cause (effectiva) of all things,
and not only gives things their existence but also in things existence with order, in so far as things are joined to one another
in order to the ultimate goal...in whatever way things change" (Aquinas De Divinis Nominibus, 4. 733).48

Does St. Thomas admit chance in the world? Yes, he does. St. Thomas states, "From the foregoing it appears that Divine
Providence does not remove fortune and chance from things" (Aquinas Summa Contra Gentiles 3. 74).49

Does St. Thomas admit equivocal cause (causa per accidens)? Yes, St. Thomas does admit equivocal cause. St. Thomas
says, "Each, that is fortune and chance, is a per accidens cause; and each is in those things which happen not necessarily
(simpliciter), that is always, nor frequently; and each is in those things which happen for the sake of something"
(Aquinas In Phys. 2. 9. 446).50 Gardeil notes the three characteristics in St. Thomas: exceptional, intentional,
not intended. The event must belong to the order of finality, something that could be an object of choice. As to the definition
of "per accidens cause," St. Thomas says, "The per accidens cause is every one which is joined to the per se
cause (the real cause or the real line of causality), but the second and per accidens cause does not have the same
nature as the first and real cause" (Aquinas In Phys. 2. 1. 6).51

Does St. Thomas hold that chance is the only source of contingency in nature? St. Thomas follows Aristotle, who says concerning
chance that "some things are for the sake of others (finalism), others not (anti-finalism)." St. Thomas holds (as do the Neo-Scholastics)
that every agent acts for an end (finalism), and so he adds the word "certain ones" (quaedam) to the text of Aristotle:
"fiunt propter finem, quaedam vero non" (Aquinas In Phys. 2. 8. 420-421).52 Aquinas is a finalist, whether
the agent acts from nature or from intellect. Aquinas explains this difficult passage in Aristotle by noting that some things
are a pleasure or a credit in themselves, and so to this extent their own end. Alternatively, Aristotle might have had in
mind some non-chance event that is not the result of deliberate action, such as a man unconsciously stroking his beard. While
this man does not act without an end; the end is in his imagination (or inner senses) but not in his intellect: it is therefore
not a deliberate end. In conclusion, Aristotle is complicated because reality is complex.

Does St. Thomas hold that Divine Providence extends even to individual created things subject to chance? Yes, St. Thomas
teaches that "Divine Providence is not opposed to contingent things subject to chance, or fortune, or human will" (Aquinas
Summa Contra Gentiles 3. 75).53

So it is true that chance and Divine Providence operate together in the universe. St. Thomas teaches that nothing happens
in the universe by pure chance alone; all is the fruit of the power and wise action of God.54

Does St. Thomas hold that Divine Providence penetrates down to the substantial change from old species to new species in
evolution? Yes, although St. Thomas does not use those words. The words St. Thomas uses specify the corruption (disappearance)
of the old form when there is the generation (substantial change) of a new form (new species). St. Thomas says, "From the
preceding, it is manifest that Divine Providence penetrates up to a chain (singularia) of things generated and corrupted"
(Aquinas Summa Contra Gentiles 3. 75).55 Therefore, Divine Providence can be involved in Evolutionism.

Does the teaching of St. Thomas concerning Divine Providence and finality lead to a useful way to understand Evolutionism?
Yes, it does. St. Thomas remarks that "Providence consists precisely in this predisposing of beings to their goal" (Aquinas
Summa Theologiae 1. 22. 1).56 But we have already noted the teaching of St. Thomas about the goal of lower
beings: "The intention of everything that is in potentiality is to tend to actuality by way of movement. Hence the more final
and the more perfect an act is, the more is the appetite of matter inclined to it. Therefore the appetite whereby matter seeks
a form must tend toward the last and most perfect act to which matter can attain, as to the ultimate end of generation. Now
certain grades are to be found in the acts of forms" (Aquinas Summa Contra Gentiles 3. 22). So Divine Providence should
"predispose beings to their goal" to which is "the last and most perfect act to which matter can attain." While St. Thomas
did not treat Evolutionism explicitly and directly, Aquinas’ doctrine of Providence and finality can be joined in what
appears to be useful way to understand Evolutionism.

Does St. Thomas teach the possibility of evolutionary finality? Yes, he does by treating obediential potency. That obediential
potency is the capacity which creatures possess to be elevated by God to acts and perfection beyond their natural power. St.
Thomas teaches: "In any creature, passive potency can be considered under two aspects: one in relation to the natural agent;
the other in relation to the Prime Mover who can bring any creature to a higher degree of perfection than the natural agent;
and under this aspect the potency is known to us as the potency of obedience of a creature" (Aquinas Summa Theologiae 3.
11. 1).57